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|
// file kernel/x/c/add.c: addition/subtraction of extensible integers
/*-----------------------------------------------------------------------+
| Copyright 2005-2006, Michel Quercia (michel.quercia@prepas.org) |
| |
| This file is part of Numerix. Numerix is free software; you can |
| redistribute it and/or modify it under the terms of the GNU Lesser |
| General Public License as published by the Free Software Foundation; |
| either version 2.1 of the License, or (at your option) any later |
| version. |
| |
| The Numerix Library is distributed in the hope that it will be |
| useful, but WITHOUT ANY WARRANTY; without even the implied warranty |
| of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
| Lesser General Public License for more details. |
| |
| You should have received a copy of the GNU Lesser General Public |
| License along with the GNU MP Library; see the file COPYING. If not, |
| write to the Free Software Foundation, Inc., 59 Temple Place - |
| Suite 330, Boston, MA 02111-1307, USA. |
+-----------------------------------------------------------------------+
| |
| Addition/soustraction |
| |
+-----------------------------------------------------------------------*/
/* +------------+
| Addition |
+------------+ */
/*
entre :
a,b = entiers extensibles
_c = NULL ou pointeur sur un entier extensible
s = 0 ou 1
sortie :
c <- a + (-1)^s*b
si _c != NULL, *_c <- c
retourne c
*/
xint xx(private_add)(xint *_c, xint a, xint b, long s) {
long la = xx_lg(a), lb = xx_lg(b);
long sa = xx_sgn(a), sb = xx_sgn(b);
long lc, sc;
xint c;
xx_push_roots_3(a,b,_c);
#ifdef caml_api
#define a __lr.a
#define b __lr.b
#define _c __lr._c
#endif
/* change le signe de b pour une soustraction */
if (s) sb ^= SIGN_m;
if (sa == sb) { /* ---------- entiers de mme signe */
/* force la >= lb */
if (la < lb) {
long l; xint x;
x = a; a = b; b = x;
l = la; la = lb; lb = l;
}
/* alloue la+1 chiffres pour c */
lc = la+1; sc = sa;
c = xx(enlarge)(_c,lc);
/* effectue l'addition */
c->val[la] = (a == c) ? xn(inc)(a->val,la,b->val,lb) :
xn(add)(a->val,la,b->val,lb,c->val);
}
else { /* --------------- entiers de signes opposs */
/* alloue max(la,lb) chiffres pour c */
lc = (la >= lb) ? la : lb;
c = xx(enlarge)(_c,lc);
/* effectue la soustraction */
if (xn(cmp)(a->val,la,b->val,lb) >= 0) {
(a == c) ? xn(dec)(a->val,la,b->val,lb) :
xn(sub)(a->val,la,b->val,lb,c->val);
sc = sa;
}
else {
(b == c) ? xn(dec)(b->val,lb,a->val,la) :
xn(sub)(b->val,lb,a->val,la,c->val);
sc = sb;
}
}
/* fixe la longueur et le signe de c */
xx(make_head)(c,lc,sc);
xx_update_and_return(_c,c);
#undef a
#undef b
#undef _c
}
/* +------------------+
| Addition mixte |
+------------------+ */
/*
entre :
a = entier extensible
b = long ou Caml/Ocaml int
_c = NULL ou pointeur sur un entier extensible
s = 0 ou 1
sortie :
c <- a + (-1)^s*b
si _c != NULL, *_c <- c
retourne c
*/
xint xx(private_add_1)(xint *_c, xint a, long b, long s) {
long la = xx_lg(a), sa = xx_sgn(a);
long sb = b & SIGN_m;
long lc;
xint c;
xx_push_roots_2(a,_c);
#ifdef caml_api
#define a __lr.a
#define _c __lr._c
#endif
/* isole la valeur absolue de b et corrige le signe pour une soustraction */
#ifdef c_api
if (sb) b = -b;
#else
b = (sb) ? -Long_val(b) : Long_val(b);
#endif
if (s) sb ^= SIGN_m;
if (la > chiffres_per_long) { /* cas |a| grand */
/* convertit b en tableau si besoin */
#if chiffres_per_long == 1
#define bb (chiffre *)&b
#elif chiffres_per_long == 2
chiffre bb[] = {b & (2*BASE_2-1), b>>HW};
#endif
if (sa == sb) { /* entiers de mme signe */
lc = la + 1;
c = xx(enlarge)(_c,lc);
if (c != a) xn(move)(a->val,la,c->val);
c->val[la] = xn(inc)(c->val,la,bb,chiffres_per_long);
}
else { /* entiers de signes opposs */
lc = la;
c = xx(enlarge)(_c,lc);
if (c != a) xn(move)(a->val,la,c->val);
xn(dec)(c->val,la,bb,chiffres_per_long);
}
}
#undef bb
else { /* cas |a| petit */
unsigned long aa, cc;
/* extrait la valeur de a */
#if chiffres_per_long == 1
aa = (la) ? a->val[0] : 0;
#elif chiffres_per_long == 2
aa = (la > 1) ? a->val[1] : 0;
if (la) aa = (aa << HW) + (unsigned long)a->val[0];
#endif
if (sa == sb) { /* entiers de mme signe */
lc = chiffres_per_long+1;
c = xx(enlarge)(_c,lc);
cc = aa + b;
c->val[0] = cc;
#if chiffres_per_long == 2
c->val[1] = cc >> HW;
#endif
c->val[chiffres_per_long] = (aa > cc);
}
else { /* entiers de signes opposs */
lc = chiffres_per_long;
c = xx(enlarge)(_c,lc);
cc = aa - b;
if (aa < cc) {sa ^= SIGN_m; cc = -cc;}
c->val[0] = cc;
#if chiffres_per_long == 2
c->val[1] = cc >> HW;
#endif
}
}
/* longueur et signe du rsultat */
xx(make_head)(c,lc,sa);
xx_update_and_return(_c,c);
#undef a
#undef _c
}
#if defined(caml_api) || defined(ocaml_api)
xint xx(add) (xint *_c, xint a, xint b) {return xx(private_add) (_c,a,b,0);}
xint xx(sub) (xint *_c, xint a, xint b) {return xx(private_add) (_c,a,b,1);}
xint xx(add_1)(xint *_c, xint a, long b) {return xx(private_add_1)(_c,a,b,0);}
xint xx(sub_1)(xint *_c, xint a, long b) {return xx(private_add_1)(_c,a,b,1);}
xint xx(f_add) (xint a, xint b) {return xx(private_add) (xx_null,a,b,0);}
xint xx(f_sub) (xint a, xint b) {return xx(private_add) (xx_null,a,b,1);}
xint xx(f_add_1) (xint a, long b) {return xx(private_add_1)(xx_null,a,b,0);}
xint xx(f_sub_1) (xint a, long b) {return xx(private_add_1)(xx_null,a,b,1);}
#endif /* defined(caml_api) || defined(ocaml_api) */
|
